Hi all,
I managed to get my Motorola HF850 handsfree unit fitted yesterday without too much trouble into my facelift with prewiring. I'm mentioned in other posts that my car had a badly fitted Nokia car kit - imagine my surprise when I removed the footwell cover under the glovebox, and down popped the Nokia HFU-2, only to find that the person who installed it had actually gone to the trouble of buying the autoleads harness for the VFA connector, but was only actually using the mute & sense leads! They had wired the 12v feed to the cigar lighter socket for some reason, and just not bothered connecting the speakers or to the GM microphone!

Just to satisfy my curiosity, I plugged the autoleads harness mic & speaker jacks into the box, and no surprise, they worked perfectly with a 6310 mobile. Still, it made my life installing the HF850 much easier.
The Motorola power connector is different to the Nokia one, so I connected it as follows:
+12v - RED - to RED on harness, VDA pin 11
GND - BLACK - to BLACK on harness, VDA pin 1
IGN - GREEN - to BLUE on harness, VDA pin 10
MUTE - ORANGE, to YELLOW on harness, VDA pin 4
I chopped the jack connectors for mic and speaker off the autoleads harness, and removed the connector from the Motorola speaker. I connected them together as follows:
SPEAKER+ - BLACK - to BLACK on harness, VDA pin 16
SPEAKER- - BLK/WHT to BLK/WHT on harness, VDA pin 7
I then powered up the unit, and tested it with the GM mic insert - no joy, so I decided to run in the Motorola mic.
(Note the connections for the GM mic are 9&14 on the VDA - I have heard that some also have a third wire connected to pin 18)
I removed the GM mic capsule from the courtesy light, and taped up the wire behind - the Motorola mic is a nice snug fit into the gap, and works perfectly:

... ran the wire down the pillar and below the glovebox. I've located the controller in front of the gearbox selector....

... then tidied up the wiring loom

...before attaching the control box (very light) to the back of the footwell panel with velcro.
They are knocking these bluetooth units for £19.99 on eBay now (were £76 not so long ago), and whilst they are not as fully featured as some of the Parrot ones etc, they are pretty good value for money.
By the way, this is what the GM mic insert looks like....

Hope you find this helpful!

- sorry if the pics are a little fuzzy - mobile 'phone job.